Communication method between a device and another device

ABSTRACT

The present invention relates to a method for communicating with another device through a first device having a Converged Personal network Service (CPNS) enabled entity. The communication method includes receiving a search request message including information regarding the mode of a second device when the CPNS enabled entity of the first device, set in the gateway mode, moves into the coverage area of a second network managed by the second device. The communication method includes: when it is confirmed that the CPNS enable entity of the second device is set with a gateway on the basis of the mode information, confirming whether there is at least one available PNE in all coverage areas of the first network and the second network; and determining whether to change the mode of the CPNS enable entity of the first device on the basis of whether there is at least one available PNE, as well as whether to change the mode of the second device. Here, according to the result of the determination, the mode of the CPNS enabled entity of the first device may be changed to a combined mode in the gateway mode.

TECHNICAL FIELD

The present invention relates to a CPNS (Converged Personal Network Service).

BACKGROUND ART

Among various developed technologies, DLNA or ZigBee is focused on discovery and use of services of devices in a specific PAN and tethering technology places emphasis on connection between heterogeneous networks.

A CPNS different from the simple PAN has been proposed.

The CPNS enables devices to belong to a PN (Personal network) (or PAN (Personal Area Network)) to be provided with various services.

The CPNS is implemented through a CPNS server, a CPNS gateway, and a device supporting the CPNS. In addition, a general server, general devices, etc. may be present for the CPNS.

The CPNS is based on a personal network corresponding to a group of devices. The CPNS gateway is located in the PN and services of the devices are registered in the CPNS server through the CPNS gateway such that a device providing a predetermined service can be discovered through the CPNS server and an external entity can share the service provided by the device on the basis of the discovery.

The CPNS gateway connects the PN (also called a gateway (GW)) to another network. The CPNS device is also called a PNE (Personal Network Entity) and is a member of the PN. A plurality of devices may be grouped to form a PNE or a single device may be a PNE.

FIG. 1 illustrates the concept of the CPNS.

Referring to FIG. 1, a general server, a CPNS server, a CPNS gateway, a CPNS device and a general device are shown.

The CPNS server can communicate with one or more CPNS gateways (that is, PN gateways) and transmit/receive data. The CPNS server can communicate with one or more CPNS devices in a PN (or PNA) through the CPNS gateway to exchange data with the CPNS devices.

Each CPNS device can transmit/receive data to/from one or more other CPNS devices or general devices through the CPNS gateway.

The CPNS gateway can communicate with the CPNS server, a CPNS gateway belonging to a different PN, or the CPNS device to transmit/receive data.

The CPNS server can communicate with general servers and the CPNS gateway to transmit/receive data.

For example, the CPNS server and the CPNS gateway can communicate with each other using a cellular network and the CPNS gateway and the CPNS device can communicate with each other using short range communication, for example, Bluetooth, NFC, ZigBee, WiFi, etc.

The CPNS server administrates and controls communication between the CPNS gateway and the CPNS device, and thus applications and information are exchanged between the CPNS gateway and the CPNS device, increasing user convenience. For example, according to the configuration of FIG. 1, a user can acquire position information using an arbitrary CPNS device from another CPNS device (e.g. GPS), transmit the position information to the CPNS server through the CPNS gateway and be provided with a location based service from the CPNS server.

Accordingly, the user can be provided with various services through a plurality of CPNS devices that belong to the PN.

DISCLOSURE Technical Problem

The above-described conventional technology proposes only the concept of the CPNS and does not provide technical specifications necessary to implement the CPNS.

Therefore, an object of the present invention is to provide a detailed technique to implement the CPNS.

Technical Solution

According to one aspect of the present invention, there is provided a method for communicating with another device through a first device including a Converged Personal network Service (CPNS) enabled entity. The method may include receiving a discovery request message including information regarding the mode of a second device when the CPNS enabled entity of the first device, set to a gateway mode, moves into the coverage of a second network managed by the second device. The CPNS enabled entity may manage a first network, and one or more entities capable of receiving a first service through the CPNS enabled entity set to the gateway mode may be present in the first network. The method may further include confirming whether one or more available PNEs are present in both coverages of the first network and the second network upon confirming that a CPNS enable entity of the second device is set to a gateway on the basis of the mode information, and determining whether to switch the mode of the CPNS enable entity of the first device on the basis of presence or absence of the one or more available PNEs and the mode of the second device. The mode of the CPNS enabled entity of the first device may be switched from the gateway mode to a combined mode according to the result of the determination.

That the mode of the CPNS enabled entity of the first device is switched to the combined mode may be determined upon confirming that the one or more entities are located outside the coverage of the second network or the one or more entities cannot directly receive a service of the second network through the second device although the one or more entities are located in the coverage of the second network.

That the mode of the CPNS enabled entity of the first device is not switched to the combined mode may be determined upon confirming that all PNEs that belong to the first network are located in the coverage of the second network and are available to receive the service of the second network.

That the mode of the CPNS enabled entity of the first device is not switched to the combined mode may be determined upon confirming that, although some PNEs belonging to the first network are not located in the coverage of the second network, the remaining PNEs that need to use the service of the second network are located in the coverage of the second network.

The available PNEs may be located in the coverage of the second network, support a communication scheme of the second network, and have sufficient power to receive the service of the second network.

The determining of whether to switch the mode of the CPNS enable entity of the first device may include the CPNS enabled entity of the first device checking mode information thereof.

The mode of the CPNS enabled entity of the first device may be switched to the combined mode upon confirming that the CPNS enabled entity is operable in the gateway mode and a PNE mode simultaneously from the checking result of the mode information of the CPNS enabled entity.

The combined mode may correspond to a mode in which the CPNS enabled entity operates in the gateway mode and PNE mode, simultaneously.

The method may further include: the CPNS enabled entity of the first device receiving service data of the second network from the second device, as a PNE, after the mode of the CPNS enabled entity is switched to the combined mode; and the CPNS enabled entity of the first device transmitting the service data to the entities, as a gateway.

The method may further include transmitting a discovery response message in response to the discovery request message.

The discovery response message may include mode information that indicates that the first device operates in the combined mode.

According to another aspect of the present invention, there is provided a device. The device may include a storage unit for storing a CPNS enabled entity set to a gateway mode. The CPNS enabled entity set to the gateway mode may manage a first network, and one or more entities capable of receiving a first service through the CPNS enabled entity set to the gateway mode may be present in the first network.

The device may further include a transceiver for receiving a discovery request message including information about the mode of a second device from the second device. The discovery request message from the second device may be received when the device moves into the coverage of a second network managed by the second device.

The device may further include a processor for confirming whether one or more available PNEs are present in both coverages of the first network and the second network upon confirming that a CPNS enable entity of the second device is set to a gateway on the basis of the mode information, and determining whether to switch the mode of the CPNS enable entity of the first device on the basis of presence or absence of the one or more available PNEs and the mode of the second device, processor switching the mode of the CPNS enabled entity of the first device from the gateway mode to a combined mode according to the result of the determination.

Advantageous Effects

According to an embodiment of the present invention, the problem of the conventional technology can be solved. That is, the embodiment of the present invention provides a detailed technique to implement the CPNS.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates the concept of the CPNS.

FIG. 2 illustrates a CPNS procedure.

FIG. 3 illustrates architecture of first and second devices shown in FIG. 2.

FIG. 4 illustrates a CPNS initial procedure.

FIG. 5 illustrates an example of overlap of a PN of a user A with another PN due to movement of the user A.

FIG. 6 shows a signal flow for switching a mode of a CPNS enabled entity and FIG. 7 is a flowchart illustrating a process of switching a mode of a CPNS enabled entity.

FIG. 8 illustrates architecture after mode change.

FIG. 9 illustrates an example of controlling synchronization after a mode of a CPS enabled entity switches.

FIG. 10 illustrates another example of controlling synchronization after a mode of a CPS enabled entity switches.

FIG. 11 is a block diagram of a device according to embodiments of the present invention.

BEST MODE

The present invention relates to a CPNS (Converged Personal Network Service). However, the present invention is not limited thereto and can be applied to any communication system and method and other systems to which the technical spirit of the present invention is applicable.

The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used in the description herein and throughout the claims that follow, “a”, “an”, and “the” includes plural references unless context clearly dictates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In the meantime, although terms including an ordinal number, such as first or second, may be used to describe a variety of constituent elements, the constituent elements are not limited to the terms, and the terms are used only for the purpose of discriminating one constituent element from other constituent elements. For example, a first component can be called a second component and the second component can be called the first component without departing from the scope of the present invention.

When a component is “connected” or “coupled” to another component, although the component can be directly connected or coupled to the other component, another component may be interposed between the two components. When a component is “directly connected” or “directly coupled” to another component, it should be understood that another component is not interposed between the two components.

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention. The preferred embodiments described in the specification and shown in the drawings are illustrative only and are not intended to represent all aspects of the invention, such that various equivalents and modifications can be made without departing from the spirit of the invention.

In the following, a terminal is shown in figures. The term ‘terminal’ may be replaced with the term ‘user equipment (UE)’, ‘mobile equipment (ME)’, ‘mobile station (MS)’, ‘user terminal ‘UT’, ‘subscriber station (SS)’, ‘wireless device’, ‘handheld device’, ‘smart phone’, etc. In addition, the terminal may be a portable device having a communication function, such as a cellular phone, PDA, smartphone, wireless modem, notebook computer, etc. or a fixed device such as a vehicle mounted device.

Definition of Terminology

Prior to description with reference to the attached drawings, terms used in the specification are briefly defined in order to assist in understanding the present invention.

1) CPNS (Converted Personal Network Service): CPNS enables devices to belong to a PN (Personal Network) (or PAN (Personal Area Network)) to be provided with various services. While the tethering service is a technique of enabling a device connected to the Internet to allocate a private IP address to another device using NAT such that the other device can access the Internet using the private IP address, the CPNS enables a first device of a user to integrate and manage services that can be provided through a mobile communication network instead of simply allocating a private IP address to another device. Since the first device of the user integrates various services and manages the services, a plurality of devices of the user can share services thereof. For example, the user can use a video on demand through the first device and then ceaselessly transmit the video on demand to a second device. Accordingly, user convenience can be improved. Furthermore, when the user has a plurality of devices, an external server can determine a device to which the external server will transmit service data, from among the plurality of devices in order to transmit the service data to the user when the user does not request the service data. For example, if the user has a plurality of devices capable of performing video call, it is possible to determine a device to which a video call request will be transmitted from among the devices upon reception of the video call request. In addition, the video call can be transferred to another device of the user without cease. The CPNS is accomplished by a CPNS enabled entity included in a device of the user.

2) CPNS enabled entity: CPNS enabled entity is a logical entity. There are three types of CPNS enabled entities. That is, a PNE, a PN GW, and a CPNS server can exist. The CPNS server entity is located in a core network and the PNE and PN GW are located in a CPNS device.

3) CPNS device: This is a device capable of simultaneously operating in multiple modes in a personal network. The CPNS device has a function of processing, storing and playing content and can include a communication interface through which different CPNS devices can operate in different modes in a personal network.

4) CPNS server: This is a function entity capable of providing resources to CPNS entities at the request of the CPNS entities or in a push manner. The CPNS server registers devices and user related services, stores corresponding information, and provides registration of a PN corresponding to a group of devices and registration of a service group including a PN and a WAN. Furthermore, the CPNS server can communicate with external entities such as a content providing server. The CPNS server is an entity that sets a key for authenticating a device of a user in order to perform a service on a CPNS framework. Moreover, the CPNS server registers externally provided services and supports discover and use/provision requests such that devices can use the externally provided services.

5) Personal network (PN): This is a set of devices through which a user can use or generate a service. All devices in a PN can be connected to a PN GW. The PN can vary with time. The PN can include at least a device operating in a GW mode and a device operating as a PNE.

6) Personal Network Element (PNE): This constitutes a PN. The PNE can use or provide a service or content. The PNE is a subject that actually consumes content, applications and services. The PNE forms a PN and a service group in the CPNS framework.

7) Personal Network Gateway (PN GW): This is an entity in a PN and a wide area network and can generate a PN providing the CPNS. Furthermore, the PN GW connects heterogeneous networks for a device that cannot be connected to an external device and administrates registration and inventory of the CPNS server for connected devices while existing in the PN.

A PN GW included in a device enables not only a PNE present in a PN but also another device to be connected to the CPNS server. The PN GW in the device uses a global network such as a mobile network. In addition, the PN GW manages services with respect to PNEs, communication and function information.

8) PN inventory: This is a list of PNs, PNEs and devices which belong to a plurality of PNs.

9) Service group: This is a set of PNEs and PN GWs which share services, data and applications and refers to a group of devices registered in a server through a generated PN. Here, all devices that are members of the service group need not belong to one PN and include all devices that are located apart from one another because they belong to different PNs and thus cannot be connected to one another. In addition, the devices need not be devices owned by the same user.

10) Zone: This refers to a specific area.

11) Zone based service: This refers to a CPNS server provided in the coverage of a zone based PN GW.

12) Zone PN GW: This is a PN GW that provides a unique service or content in a zone.

13) CPNS enabled entity mode: A CPNS device can operate in PN GW and PNE modes. These modes can be confirmed among devices through a CPNS entity discovery function. A PN needs to include at least a device operating in the PN GW mode and a PNE operating in the PNE mode. A PNE and a PN GW need to know modes thereof each other in order to generate or participate in a PN. The PN GW needs to identify the PNE in order to generate a member of the PN. Furthermore, the PNE needs to newly generate a PN or to participate in a previously generated PN.

When there is a device (e.g. MP3 player, smart meter or the like) which supports only the PNE mode, the device needs to operate only in the PNE mode. If a certain device can operate only in the PN GW mode, this device operates in the PN GW mode. However, if a certain device can operate in one of the PN GW mode and the PNE mode, the mode of this device can be set according to a previously stored set value or be changed according to user setting or service provider setting.

FIG. 2 illustrates a CPNS procedure.

FIG. 2 shows a first device 110, a second device 120, a CPNS server 300, and an application server 400.

The first and second devices 110 and 120 are owned by a user A. The first device 110 is a cellular phone of the user A and may include a first transceiver through which the first device 100 can be connected to the CPNS server 300 via a mobile communication network. Furthermore, the first device 100 may include a second transceiver, such as Bluetooth, WiFi, ZigBee, etc., to form a personal network. The second device 120 is a portable multimedia device of the user A and may include only the second transceiver such as Bluetooth, WiFi, ZigBee, etc. to form the personal network without having the first transceiver capable of communicating with a mobile communication network.

The first and second devices 110 and 120 can respectively include CPNS enabled entities. Each CPNS enabled entity can operate in a gateway mode or a PNE (Personal Network Entity) mode. FIG. 2 shows that the CPNS enabled entities operate in the gateway mode since the second device 120 has the first transceiver that can be connected through the mobile communication network.

When the first device 110 and the second device 120 are located close to each other, the first and second devices 110 and 120 perform a physical connection procedure through the second transceivers thereof. The application server 400 registers services and content in the CPNS server 300 or advertises the services and content. The CPNS server 300 authenticates the second device 120 operating as a gateway.

Upon completion of the physical connection procedure of the first device 110 and the second device 120, the CPNS enabled entities of the first and second devices 110 and 120 discover each other.

Upon completion of discovery, the devices set up PN#1. Here, information about PN#1 is registered in the CPNS server 300.

When PN#1 has been set up, the CPNS server 300 advertises services registered therein to devices belonging to PN#1 or searches for services that can be provided by the devices included in PN#1.

When an arbitrary device belonging to PN#1 invokes an arbitrary service or content from among the advertised services, the function of the arbitrary device is checked and the service or content is transmitted according to the checked function.

When the arbitrary device uses the service or content, statistics about use of the service or content are collected and reported to the CPNS server 300 or the application server 400.

When PN#1 is not needed any more, PN#1 is cancelled and the information about PN#1, registered in the CPNS server 300, is also cancelled.

FIG. 3 illustrates architecture of first and second devices shown in FIG. 2.

As shown in FIG. 3, each of the first and second devices 110 and 120 includes a physical layer, a MAC layer, a third layer, a CPNS enabled entity, and an application layer. The CPNS enabled entity of the second device 120 operates in the PNE mode and the CPNS enabled entity of the first device 110 operates only a gateway entity.

Accordingly, service data is transmitted to the gateway entity in the CPNS enabled entity of the first device 110 through the physical layer, MAC layer, and third layer of the first device 110, as indicated by a thick solid line in FIG. 3. When the gateway entity of the first device 110 receives the service data, the service data is transmitted to the second device 120 through the CPNS enabled entity, third layer, MAC layer and physical layer of the first device 110.

A PNE included in the CPNS enabled entity of the second device 120 receives the service data through the physical layer, MAC layer and third layer of the second device 120.

The PNE in the CPNS enabled entity of the second device 120 transmits a control message such as a request message or a response message to the first device 100 through the third layer, MAC layer and physical layer.

FIG. 4 illustrates a CPNS initial procedure.

As shown in FIG. 4, a pairing process S11 corresponding to a physical connection procedure, an entity discovery process S12 and a PN establishment process S13 are performed.

In the pairing process S11, physical connection between devices of the user A is initiated.

To achieve this, the second device 120 starts to perform scanning. For scanning, the second device can transmit a scan message to the first device 110. The first device 110 transmits a scan answer message to the second device 120 to respond to the scan message. Then, physical connection between the first device and the second device is initiated and information for physical connection, e.g., addresses, IP addresses, etc. are exchanged. After information exchange, the second device transmits a physical connection request message, for example, a pairing request message to the first device. The first device receives a pin code from the user, embeds the pin code in a connection request answer message, for example, a pairing answer message, and transmits the pairing answer message including the pin code to the second device. If the pin code is correct, the physical connection procedure is completed.

Upon completion of physical connection, the CPNS enabled entities included in the devices discover each other, that is, perform the entity discovery process S12.

Specifically, the CPNS enabled entity of the second device 120 transmits a discovery request message, for example, entity discovery request message to the first device 110. The discovery request message, for example, the entity discovery request message includes information about the mode of the CPNS enabled entity included in the second device and information about the CPNS enabled entity and previously discovered other devices. If the CPNS enabled entity included in the second device is set to a gateway, the information about the mode of the CPNS enabled entity can include information representing the gateway.

The CPNS enabled entity included in the first device 100 also transmits a discovery request message, for example an entity discovery request message to the second device 120. The discovery request message, for example, the entity discovery request message includes information about the mode of the CPNS enabled entity included in the first device and information about the CPNS enabled entity and previously discovered other devices. If the CPNS enabled entity included in the first device is set to a PNE (Personal Network Entity), the information about the mode of the CPNS enabled entity can include information that represents the PNE.

The CPNS enabled entity of the first device 110 transmits a discovery response message, e.g., an entity discovery response message to the second device 120 in response to the discovery request message received from the second device. The discovery response message, e.g., the entity discovery response message includes mode information, information about the CPNS enabled entity and other previously discovered devices, and information about a UI function.

Similarly, the CPNS enabled entity of the second device 120 transmits a discovery response message, for example, an entity discovery response message to the first device 110 in response to the discovery request message received from the first device.

Upon completion of a discovery procedure using the above-mentioned signals, the PN establishment process S13 is performed.

Specifically, when the CPNS enabled entity of the second device 120 is set to a gateway, the second device 120 transmits a PN establishment request message, for example, a PN setup request message to a device set to a PNE, for example, the first device 110. Here, the PN setup request message may include information about the gateway and information about entities (e.g. the CPNS enabled entity included in the first device) that will belong to a PN to be generated.

When the CPNS enabled entity of the first device transmits a PN setup response message to the second device, the CPNS enabled entity of the second device 120 transmits the PN setup request message to the CPNS server 300.

Upon reception of the PN setup request message, the CPNS server 300 transmits an authentication request message to the first device through the second device 120 operating as a gateway. The first device transmits an authentication response message to the CPNS server 300 through the second device operating as a gateway in response to the authentication request message received from the CPNS server 300.

Upon reception of the authentication response message, the CPNS server 300 transmits the PN setup response message to the second device 120 operating as a gateway.

Then, the CPNS enabled entity of the second device 120 operating as a gateway transmits a PN establishment notification message to the first device.

When PN setup is completed according to transmission and reception of the above-mentioned messages, the application server 400 such as a content server can transmit a service description advertisement message including information about services of the application server 400 to the second device 120 corresponding to the gateway through the CPNS server 300. Then, the second device 120 corresponding to the gateway transmits the service description advertisement message to devices that belong to a PN managed by the second device 120.

FIG. 5 illustrates an example of overlap of a PN of the user A with another PN due to movement of the user A.

FIG. 5( a) shows three PNs, a CPNS server and an application server. PN#1 from among the three PNs is generated by the user A. PN#1 includes devices of the user A. For example, PN#1 can include GW#1 and PNE#1. It is assumed that GW#1 is a cellular phone of the user A and PNE#1 is a portable multimedia device of the user A. PN#2 includes GW#2 and PNE#2, and PN#3 includes GW#3 and PNE#3. The application server can provide services to the PNEs of the PNs through the CPNS server, GW#1, GW#2 and GW#3.

It is assumed that the user A moves into the coverage of PN#2 while carrying GW#1, as shown in FIG. 5( b).

Then, PN#1 including GW#1 overlaps with PN#2. That is, GW#1 and PNE#1 of the user A are within in the coverage of PN#2. Here, PNE#1 may move with the user A into the coverage of PN#2. However, while PNE#1 is within the coverage of PN#2, PNE#1 may not be connected with GW#2 included in PN#2 due to power shortage, power off, or a difference between communication schemes of PNE#1 and PN#2. Otherwise, if the user A carries only GW#1 leaving PNE#1 in a vehicle, PNE#1 may be located outside the coverage of PN#2.

When PNE#1 cannot be connected with GW#2 in PN#2 for the above-mentioned reason, the user A has no terminal through which a service can be received from GW#2 in PN#2.

Accordingly, GW#1 of the user A needs to operate as a PNE in order to receive the service since GW#1 is a gateway. A description will be given of processes for switching the mode of GW#1 from the gateway mode to other modes.

FIG. 6 shows a signal flow for switching a mode of a CPNS enabled entity and FIG. 7 is a flowchart illustrating a process of switching a mode of a CPNS enabled entity.

FIG. 6 illustrates a process of switching the mode of the CPNS enabled entity of the first device 120 from the gateway mode to other modes according to a first embodiment of the present invention.

Specifically, the user A has the first device 100 operating as a gateway and the second device 120 operating as a PNE, as shown in FIG. 6. It is assumed that the first device 110 is a cellular phone and the second device 120 is a portable multimedia device.

1) to 4) When the first device 110 and the second device 120 are located close to each other, a physical connection process is performed. The CPNS enabled entity included in the first device 110 reads a mode set value thereof, activates a gateway entity according to the mode set value and deactivates a PNE. Similarly, the CPNS enabled entity included in the second device 120 reads a mode set value thereof, activates a PNE according to the mode set value and deactivates a gateway entity. Subsequently, the first device 110 and the second device 120 discover each other. The CPNS enabled entity of the first device 110 performs a PN setup process to generate PN#1.

5) It is assumed that the user A moves into the coverage of PN#2 while carrying the first device 110. In this case, the second device may be located outside the coverage of PN#2 or may not communicate with PN#2 although it is located inside the coverage of PN#2 due to insufficient battery capacity, power off, a difference between communication schemes of the second device and PN#2, etc.

Then, the user A performs physical connection of the first device 110 and a third device 210.

6) Upon completion of physical connection, a CPNS enabled entity included in the third device 210 transmits a discovery request message when the mode thereof is set to the gateway mode. In this case, if the CPNS enabled entity included in the third device 210 and the CPNS enabled entity included in the first device 110 simultaneously transmit the discovery request message, information may overlap. To prevent this, the third device 210 operating as a gateway transmits the discovery request message first immediately after physical connection is completed.

The discovery request message may include the following elements.

-   -   EntityInfo element: This includes information about a CPNS         enabled entity that transmits the discovery request message.     -   UserInfo element: This includes information about the user of         the CPNS enabled entity that transmits the discovery request         message. The information about the user may include a user ID         and a user name as lower elements.     -   PNEID element (or attribute): This is the ID of a PNE when the         CPNS enabled entity that transmits the discovery request message         corresponds to the PNE.     -   PN GW ID element (or attribute): This is the ID of a PN GW when         the CPNS enabled entity that transmits the discovery request         message corresponds to the PN GW.     -   PNE name or PN GW name element: This is the name of a PNE when         the CPNS enabled entity that transmits the discovery request         message corresponds to the PNE, or the name of a PN GW when the         CPNS enabled entity that transmits the discovery request message         corresponds to the PN GW.     -   Mode element (or attribute): This is information about an         activated mode of the CPNS enabled entity that transmits the         discovery request message, which has a value indicating a PNE or         a PN GW. This information has a value of 1 when the activated         mode of the CPNS enabled entity corresponds to a PNE and has a         value of 2 when the activated mode of the CPNS enabled entity         corresponds to a PN GW. Since the CPNS enabled entity of the         third device is set to a gateway in FIG. 6, the information         includes a value of 2.     -   PN Info Req element (or attribute): This has a value of ‘True’         or ‘False’. This element has the value ‘True’ when the CPNS         enabled entity that transmits the discovery request message         wants to acquire information about a PN, which is stored in an         entity that will receive the discovery request message.     -   UI capabilities element (or attribute): This has a value ‘True’         when a PN GW instead of a PNE needs to perform user interaction.         This element is set by a PNE. The element can be set to the         value ‘True’ when the PN GW performs user interaction because         the PNE has no user interface.     -   Zone based service support element (or attribute): This is set         to ‘True’ when the PN GW can provide a zone based service.     -   PN Info element: This is included in the discovery request         message when the CPNS enabled entity that transmits the         discovery request message is a PN GW and includes a PN ID lower         element, a PNE Info lower element, etc. The PN ID lower element         represents the ID of a PN when the PN is previously present and         the PNE Info lower element includes information about a PNE         belonging to a PN when the PN is previously present. The PNE         Info lower element includes a PNE ID element and a PNE name         element.

After generation of the discovery request message, the gateway transmits the discovery request message to discovered devices through physical connection. The discovery request message can be transmitted in a broadcast manner.

The discovery request message may have a configuration shown in Table 1.

TABLE 1 Element Description UserInfo This includes UserID and UserName. User ID ID of CPNS user UserName CPNS user name Entity This is an abbreviation for Entity information. Info This can include the following lower elements. PNEID, PNGWID, Name, Mode, PN Info Req, UI Capa, Zone based service support, Broadcast group key delivery support PNEID ID of a PNE PNGWID ID of a PN GW Name Name of the PNE or PN GW Mode Mode of a transmission subject. This is 1 when the PNE is a transmission subject and 2 when the PN GW is a transmission subject. This is 3 when a transmission subject can operate as the PNE and GW simultaneously. PNInfoReq This is set to ‘True’ when PN Info is requested when the PNE transmits the message. UICapa This is set to ‘True’ when the PN GW interacts with the user since a device operating as a PNE has no user interface. Zone based This is set to ‘True’ when the PN GW service provides a zone based service. support PN Info This includes information about a PN such that a PNE joins the PN when a PN GW transmits the discovery request message and has the PN. This can include PN ID, Description, and PNE Info lower element. PNID ID of a PN Description Description about the PN PNE Info This includes information about PNEs that are members of the PN. This can include PNEID and PNE name as lower elements. Furthermore, this can include Device Info as a lower element. PNEID ID of a PNE PNEName Name of the PNE Device This is information about a Info device. This can include a Mode element and InactiveMode. Mode This can include information about a currently activated mode. Inactive This includes Mode information about an inactivated mode.

As shown in FIG. 7, the CPNS enabled entity of the first device 110 confirms a provided service by checking an element about the service, for example, ‘zone based service support’ in the received discovery request message (S111). When the provided service is one desired by the user A, the next process is performed.

The CPNS enabled entity of the first device 110 checks the mode of a counterparty that has transmitted the discovery request message through the mode element on the basis of the received discovery request message and checks the ID of the counterparty through the EntityInfo element.

8) and 9) The CPNS enabled entity of the first device 110 checks states of PNEs that belong to PN#1 (S112). When there is no PNE that can use the service provided by PN#2, the CPNS enabled entity of the first device 110 checks the mode thereof (S113). The fact that there is no PNE capable of using the service provided by PN#2 may mean that none of PNEs located in the coverage of PN#1 is located in the coverage of PN#2, or mean that there is no PNE capable of communicating with PN#2 due to insufficient battery capacity, power off, communication scheme difference, etc. although one or more PNEs are located in both the coverage of PN#1 and the coverage of PN#2.

Whether there is a PNE that can use the service provided by PN#2 can be determined with reference to the following table 2.

TABLE 2 Presence in overlap Presence inside area of coverage of coverage of PN #1 PN #1 and coverage but outside Determination of PN #2 coverage of PN #2 result Available PNE is PNE is present. Mode switch is present. required. Available PNE is PNE is not present. Mode switch is not present. required. Available PNE is PNE is present. Mode switch is not present. required. Available PNE is PNE is not present. Mode switch is not not present. required.

10) When the CPNS enabled entity of the first device 10 can operate as a PNE as well as a gateway, the PNE is activated (S114). Upon activation of the PNE, both the gateway mode and the PNE mode are activated. Simultaneous activation of the two modes is called a ‘both mode’ or ‘combined mode’.

11) When the checked mode of the counterparty is the GW mode, it is determined that an additional discovery request message is not transmitted, and a discovery response message is generated.

Here, when the CPNS enabled entity of the first device 110 activates the PNE as well as the gateway, mode information included in the discovery response message, for example, entity discovery response message in response to the discovery request message is set to ‘both mode’ or ‘combined mode’ and transmitted.

-   -   Entity Info element: Information about a CPNS enabled entity         that receives the discovery request message, which includes a         User ID and a user name as lower elements.     -   PNE ID element: This includes the ID of a PNE when the CPNS         enabled entity that receives the discovery request message is         the PNE.     -   PNE Name element: This includes the name of a PNE when the CPNS         enabled entity that receives the discovery request message is         the PNE.     -   Mode element: This is set to ‘both mode’ or ‘combined mode’.     -   UI Capa element: This has a value ‘True’ when a PN GW instead of         a PNE performs user interaction. This is set by the PNE. For         example, this element can be set to a value ‘True’ when the PN         GW interacts with the user since the PNE has no user interface.     -   PN Info element: This element is included in the discovery         response message when the PN Info Req element has been set to         ‘True’ in the received discovery request message. The first         device 110 includes information about PN#1 generated by the         first and second devices 110 and 120 in this element when the PN         Info Req element has been set to ‘True’ in the received         discovery request message. The PN Info element can include a PN         ID, description, etc. as lower elements.     -   PNE Info element: This element includes information about         members of a PN.

The above-described discovery response message may have a configuration shown in the following table 3.

TABLE 3 Element Description UserInfo This includes UserID and UserName User ID ID of a user UserName Name of the user Entity This is an abbreviation for entity information. Info This can include the following lower elements. PNEID, PNGWID, Name, Mode, PN Info Req, UI Capa PNEID ID of a PNE PNGWID ID of a PN GW Name Name of the PNE or PN GW Mode Mode of a subject that transmits a discovery response message. This is 1 when the PNE transmits the discovery response message and is 2 when the PN GW transmits the discovery response message. This is 3 when the PNE and GW can simultaneously operate. UICapa This is set to ‘True’ when the PN GW interacts with the user since a device operating as the PNE has no user interface. PN Info This includes information about a PN when the PNE transmits the discovery response message and has joined another PN. This can include PN ID, Description, and PNE Info as lower elements. PNID ID of a PN Description Description about the PN PNE Info This includes information about PNEs that are members of the PN. This can include PNEID and PNE name as lower elements. Furthermore, this can include Device Info as a lower element. PNEID ID of a PNE PNEName Name of the PNE Device This is information about a Info device. This can include a Mode element and InactiveMode element. Mode This can include information about a currently activated mode. Inactive This includes information about Mode an inactivated mode.

Upon checking that the CPNS enabled entity of the first device 110 operates in the ‘both mode’ or ‘combined mode’ in which the CPNS enabled entity operates as a PNE as well as a gateway, the third device 210 starts a PN#2 setup process through which the first device 110 joins PN#2 to which the third device 210 belongs. This is described in more detail below.

12) The CPNS enabled entity of the third device 210 transmits a PN setup request message to the first device 110. Here, the PN setup request message may include information about the gateway and information about entities (e.g. CPNS enabled entity included in the first device) that will belong to a PN to be generated.

The PN setup request message may have a configuration shown in Table 4.

TABLE 4 Element Description Origin ID of a CPNS entity for which a PN will be set up Entity ID PN This represents how the PN is set up. Setup 1: PN GW and PNE one-to-on correspond to each other Type and are included in the PN. 2: PNE sets up the PN with all devices connected to PN GWs. 3: PN is set up only with invited specific PNEs. Invited This includes IDs of PNEs that will be invited during PNE ID PN setup process. PN Info This is information about a PN that will be registered and stored in a CPNS server and can include the following elements. PNID, Description, Disclosure, Ownership Entity, PN GW Info, PNE Info PN ID This represents ID of a PN. Description This represents description of the PN (e.g. home, office). PN GW Info This is information about a PN GW and includes PNGWID and PN GW Name elements. PNGWID ID of a PN GW PN GW Name Name of the PN GW PNE Info This is information about a PNE and can include PNEID, PNE Name, Mode, Description, Device Capa, and Service profile elements. PNE ID ID of a PNE PNE Name Name of the PNE Mode Information about the mode of the PNE Description Description of the PN Device Capa Information about functions of a device including a PNE Service Information about CPNS Profile enabled applications or information about content supporting a specific service or status Auth This is information used to start PNE authentication IniData and can include AuthPNEID, rand_PNE, LocalEUKeyAssignment. AuthPNEID ID of a target PNE that needs to be authenticated by the CPNS server Rand_PNE Random value generated by a PNE LocalEUKey Flag representing necessity of LocalEUKey Assignment assignment TRUE: necessary, FALSE: unnecessary

13) When the CPNS enabled entity operating as a PNE in the first device 110 receives the PN setup request message, the PNE checks the Origin Entity ID element in order to find out the entity that attempts to generate the PN. Then, the PNE extracts PN ID and Msg ID elements from the PN setup request message.

The CPNS enabled entity operating as the PNE in the first device 110 generates a PN setup response message as follows.

The CPNS enabled entity operating as the PNE includes a response to the PN setup request message in a Return element included in the PN setup response message. The response is ‘1’ when the CPNS enabled entity can process the PN setup request and ‘2’ when the CPNS enabled entity cannot process the PN setup request. Subsequently, PN Info element about PN information stored in the CPNS enabled entity of the first device 110 is included in the PN setup response message. Then, information about a PNE that belongs to the PN, which is stored in the CPNS enabled entity of the first device 110, is included in a PNE Info element in the PN setup response message. In addition, various elements are included in the PN setup response message.

The message generated in this manner may have a configuration shown in Table 5.

TABLE 5 Element Description Return This represents whether PN setup request is successfully processed. 1: OK 2: Fail, CPNS enabled entity cannot process PN setup request 3: Not permitted PN Info This is information about a PN and can include PNID, Description, PNGWInfo, and PNEInfo. PN ID ID of a PN Description Description of the PN PN GW Info This is information about a PN GW and includes PNGWID and PN GW Name elements. PNGWID ID of a PN GW PNGW Name Name of the PN GW PNE Info This is information about a PNE and can include PNEID, PNEName, Mode, Description, DeviceCapa, and Serviceprofile. PNEID ID of a PNE PNEName Name of the PNE Mode Information about the mode of the PNE Description Description of PN Device Capa Information about functions of a device including a PNE Service Information about CPNS Profile enabled applications or information about content supporting a specific service or status Auth This is information use to start PNE authentication IniData and can include AuthPNEID, rand_PNE, LocalEUKeyAssignment. AuthPNEID ID of a target PNE that needs to be authenticated by the CPNS server Rand_PNE Random value generated by a PNE LocalEUKey Flag representing necessity of LocalEUKey Assignment assignment TRUE: necessary, FALSE: unnecessary Auth This is information used for a PNE to FinData authenticate a CPNS server and includes HASH. HASH Hash value calculated by a target PNE or PN GW.

Upon generation of the PN setup response message, the CPNS enabled entity of the first device transmits the generated message to the third device 120.

14) When the CPNS enabled entity of the third device 210 receives the PN setup response message, the CPNS enabled entity of the third device 210 checks the Return element included in the received message in order to check whether the first device wants to join the PN. When the Return element is set to ‘1’, the CPNS enabled entity of the third device 210 generates information about a PN inventory for the PN, creates a routing table on the basis of information from the received message and maintains the routing table.

The CPNS enabled entity of the third device 210 generates a PN setup request message to be transmitted to the CPNS server.

Specifically, the CPNS enabled entity of the third device 210 embeds the ID of the PN GW in an OriginEntityID element. The CPNS enabled entity of the third device 210 includes information about the PN to be generated in a PN Info element of the PN setup request message. Here, the PN Info element includes a PN ID element including the ID of the PN generated by the PN GW, Description element including description of the PN, etc. In addition, the CPNS enabled entity of the third device 210 embeds a PN GW Info element in the PN setup request message. Here, the PN GW Info element includes a PN GW ID element that represents the ID of the PN GW and PN GW Name element that represents the name of the PN GW. Furthermore, the CPNS enabled entity of the third device 210 includes a PNE Info element and an Auth Ini Data element in the PN setup request message.

Particularly, the CPNS enabled entity of the third device 210 includes a value representing that the first device 110 operates in the ‘both mode’ or ‘combined mode’ in a lower Mode element of the PNE Info element. That is, the PNE ID is set to PNE#0 and Mode is set to ‘Both’ in the PNE Info element, as shown in FIG. 6.

Upon generation of the PN setup request message, the CPNS enabled entity of the third device 210 transmits the generated PN setup request message to the CPNS server 300.

15) Upon reception of the PN setup request message from the third device 210, the CPNS server 300 generates an authentication request message and transmits the authentication request message to the first device 110 through the third device 210.

16) The first device 110 transmits an authentication response message to the CPNS server 300 through the third device 210.

When authentication is successful from the result of checking the authentication response message, the CPNS server 300 registers PN information included in the PN setup request message and stores the PN information in the PN inventory.

17) The CPNS server 300 generates a PN setup response message and transmits the PN setup response message to the third device 210.

18) Upon reception of the PN setup response message from the CPNS server 300, the third device 210 stores the PN information in a local PN inventory. The third device 210 generates a PN establishment notification message and transmits the PN establishment notification message to the first device 110.

When PN#2 has been set up through the above procedure, the application server 400 can acquire information about PN#2 from the CPNS server 300 and, when service data is present, determine the first device 110 or the second device 120 as a destination of the service data through the acquired information. When the application server 400 determines the second device 120 as the destination of the service data, the application server 400 transmits the service data to the third device operating as a gateway and the third device 210 delivers the service data to the first device 110 operating as a PNE. When the CPNS enabled entity operating as a PNE in the first device 110 receives the service data, the CPNS enabled entity transmits the service data to an interval gateway and the internal gateway delivers the service data to the second device 120.

When the CPNS enabled entity of the first device 110 operates in ‘Both mode’, the gateway and PNE simultaneously operate in the CPNS enabled entity of the first device 110 and a communication channel is set up between the gateway and the PNE, as illustrated in FIG. 8. Accordingly, the CPNS enabled entity of the first device 110 receives the service data from the third device 210, which operates as a gateway in PN#2, as a PNE. The CPNS enabled entity of the first device 110 delivers the service data to the second device 120, which operates as a PNE in PN#2, as a gateway.

More specifically, as shown in FIG. 8, the physical layer, MAC layer, third layer, CPNS enabled entity and application layer are present in each of the first, second and third devices 110, 120 and 210. The CPNS enabled entity of the second device 120 drives only the PNE and the CPNS enabled entity of the third device 210 drives only the a gateway entity. The CPNS enabled entity of the first device 110 drives both the PNE and gateway when the first device 110 is switched to ‘both mode’ or ‘combined mode’. Furthermore, a communication link is established between the PNE and the gateway entity in the CPNS enabled entity of the first device 110 as shown in FIG. 8.

Accordingly, service data is transmitted to the first device 110 through the CPNS enabled entity, third layer, MAC layer and physical layer of the third device 210. When the first device 110 receives the service data, the PNE of the CPNS enabled entity of the first device 110 receives the service data through the physical layer, MAC layer and third layer of the first device 110 and delivers the service data to the gateway entity through the communication link established between the PNE and the gateway entity. The gateway entity in the CPNS enabled entity of the first device 110 transmits the service data to the second device 120 through the third layer, MAC layer and physical layer of the first device 110.

When the CPNS enabled entity included in the first device 110 communicates as a PNE with the third device 210 operating as a gateway and, at the same time, communicates as a gateway with the second device 120 operating as a PNE, synchronization needs to be adjusted.

In other words, if synchronization is not achieved when the CPNS enabled entity of the first device 110 simultaneously communicates with the third device 210 and the second device 120, communication with one device may act as interference in communication with the other device. For example, a signal transmitted from the third device 210 to the first device 110 may become interference in the second device 120. Similarly, a signal transmitted from the second device 120 to the first device 110 may act as interference in the third device 120.

To avoid this interference, synchronization of the communication link between the first device 110 and the second device 120 needs to be readjusted according to synchronization of the communication link between the third device 210 and the first device 110.

This is described in detail with reference to FIGS. 9 and 10.

FIG. 9 illustrates an example of adjusting synchronization after the mode of a CPS enabled entity switches.

The upper part of FIG. 9( a) shows transmission (Tx) and reception (Rx) cycles in PN#1 composed of the first device 110 and the second device 120, and the lower part of FIG. 9( a) shows transmission (Tx) and reception (Rx) cycles in PN#2 composed of the first device 110 and the third device 210. As shown in FIG. 9( a), an idle time T1 in PN#1 may be longer than an idle time T2 in PN#2.

Accordingly, a signal transmitted from the third device 210 to the first device 110 in PN#2 may interfere with the second device 120 in PN#1.

To solve the above-mentioned desynchronization, the first device 110 can measure a start point T0 in the link between the first device 110 and the third device 210. Furthermore, the first device 110 can measure one of more of Tx cycle, Rx cycle and idle time between Tx and Rx with respect to the third device 210.

The first device 110 can transmit a control signal for adjusting synchronization with the second device 120 to the second device on the basis of one or more of the measurement results. Here, the control signal can include one or more of the measurement results.

The second device 120 can readjust synchronization with the first device 110 on the basis of the control signal.

Upon readjustment of synchronization, the idle time T1 and the idle time T2 can be equal to each other, as shown in FIG. 9( b). Furthermore, Tx cycles can correspond to each other and Rx cycles can correspond to each other.

FIG. 10 illustrates another example of adjusting synchronization after the mode of a CPS enabled entity switches.

The upper part of FIG. 10( a) shows an operation of the first device 110 to receive data from the third device 210 and the lower part thereof shows an operation of the first device 110 to receive data from the second device 120. In FIG. 10( a), a time during which the first device 110 applies power to an internal receiver thereof in order to receive a beacon signal from the third device 210 is represented as ‘wakeup time 1’ and a time during which the first device 110 supplies power to the internal receiver thereof in order to receive a beacon signal from the second device 120 is represented as ‘wakeup time 2’.

As shown in FIG. 10( a), the first device 110 needs to apply power to the receiver for wakeup time 1 and wakeup time 2 in order to receive the beacon signals.

Accordingly, power can be used more efficiently if it is possible to reduce the time for which power is applied to the received.

To achieve this, the first device 110 compares an offset between the time when the beacon signal is received from the third device 210 and the time when the beacon signal is received from the second device 210 with the wakeup time 1. If the offset is longer than the wakeup time 1, the offset can be reduced. To decrease the offset, the first device 110 can transmit a control signal to the second device 120.

Referring to FIG. 10( b), it is assumed that a time during which the first device 110 applies power to the internal receiver thereof in order to receive a beacon signal from the third device 210 is wakeup time 1, a time before the beacon signal is received in the wakeup time 1 is a time a1, and a time after the beacon signal is received in the wakeup time 1 is a time a2. In addition, it is assumed that a time during which the first device 110 applies power to the internal receiver thereof in order to receive a beacon signal from the second device 120 is wakeup time 2, a time before the beacon signal is received in the wakeup time 2 is a time b1, a time after the beacon signal is received in the wakeup time 2 is a time b2, and a time offset between the wakeup time 1 and wakeup time 2 is k.

The first device 110 compares a2+b1 with k. If a2+b1<k, the first device 110 decreases k. To decrease k, the first device 110 can transmit a control signal to the second device 120.

The above-described embodiments can be combined. Accordingly, the embodiments can be implemented not only solely but also in a combined manner as necessary. This combination can be easily implemented by those skilled in the art, and thus it will not be described in detail. However, such combination is within the scope of the present invention even if it is not described.

The embodiments of the present invention may be achieved by various means, for example, hardware, firmware, software, or a combination thereof.

In a hardware configuration, the methods according to the embodiments of the present invention may be achieved by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSDPs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

In a firmware or software configuration, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, etc. Software code may be stored in a memory unit and executed by a processor. The memory unit is located at the interior or exterior of the processor and may transmit and receive data to and from the processor via various known means.

For example, the method according to the present invention can be stored in a storage medium (e.g., internal memory, flash memory, hard disk, etc.) and be implemented as codes or commands in a software program executable by a processor (e.g., microprocessor). This is described with reference to FIG. 11.

FIG. 11 is a block diagram of a device according to the embodiments of the present invention.

As shown in FIG. 11, the first device 110 includes a storage unit 111, a controller 112 and a transceiver 113.

The storage unit 111 stores the methods illustrated in FIGS. 2 to 10.

The controller 112 controls the storage unit 111 and the transceiver 113. Specifically, the controller 112 executes the methods stored in the storage unit 112. The controller 112 transmits the above-mentioned signals through the transceiver.

The exemplary embodiments described hereinabove are combinations of elements and features of the present invention. The elements or features may be considered selective unless otherwise mentioned. Each element or feature may be practiced without being combined with other elements or features. Further, the embodiments of the present invention may be constructed by combining parts of the elements and/or features. Operation orders described in the embodiments of the present invention may be rearranged. Some constructions of any one embodiment may be included in another embodiment and may be replaced with corresponding constructions of another embodiment. The present invention may be embodied by a combination of claims which do not have an explicitly cited relation in the appended claims or may include new claims by amendment after application.

Those skilled in the art will appreciate that the present invention may be carried out in other specific ways than those set forth herein without departing from the spirit and essential characteristics of the present invention. The above embodiments are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention should be determined by the appended claims and their legal equivalents, not by the above description, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein. Therefore, the present invention intends not to limit the embodiments disclosed herein but to give a broadest range matching the principles and new features disclosed herein. It is obvious to those skilled in the art that claims that are not explicitly cited in each other in the appended claims may be presented in combination as an embodiment of the present invention or included as a new claim by a subsequent amendment after the application is filed. 

The invention claimed is:
 1. A method for communicating with another device through a first device, the method comprising: receiving a discovery request message including information regarding a mode of a second device when the first device, set to a gateway mode, moves into the coverage of a second network managed by the second device, wherein the first device is configured to manage a first network, one or more devices capable of receiving a first service through the first device set to the gateway mode being present; confirming whether one or more available devices are present in both coverages of the first network and the second network if it is checked that the second device is set to a gateway mode based on the information regarding the mode of the second device; and determining whether to change the mode of the first device based on: presence or absence of the one or more devices that can be served by the second network from among devices in the coverage of the first network; and the mode of the second device, and changing the mode of the first device from the gateway mode to a combined mode according to the result of the determination, and wherein the combined mode is a mode in which the first device operates as both of a gateway of the first network and a member of the second network, simultaneously.
 2. The method according to claim 1, wherein the changing is done if the one or more devices are located outside the coverage of the second network or the one or more devices cannot directly receive a service of the second network through the second device although the one or more devices are located in the coverage of the second network.
 3. The method according to claim 1, wherein the changing is not done if all devices that belong to the first network are located in the coverage of the second network and are available to receive the service of the second network.
 4. The method according to claim 1, wherein the changing is not done if some devices belonging to the first network are not located in the coverage of the second network, but the remaining devices that need to use the service of the second network are located in the coverage of the second network.
 5. The method according to claim 1, wherein the available devices are located in the coverage of the second network, support a communication scheme of the second network, and have sufficient power to receive the service of the second network.
 6. The method according to claim 1, wherein the determining comprises checking information regarding a mode of the first device.
 7. The method according to claim 6, wherein the changing is done if the first device is operable in both of the gateway mode and a non-gateway mode simultaneously.
 8. The method according to claim 1, further comprising: receiving service data of the second network from the second device after the mode of the first device is changed to the combined mode; and transmitting the service data to the devices in the first network.
 9. The method according to claim 1, further comprising transmitting a discovery response message in response to the discovery request message.
 10. The method according to claim 9, wherein the discovery response message includes mode information that indicates that the first device operates in the combined mode.
 11. A device, comprising: a transceiver for receiving and/or transmitting signal to other devices; and a processor for controlling the transceiver, wherein the processor is configured to: receive a discovery request message including information regarding a mode of a second device when the first device, set to a gateway mode, moves into the coverage of a second network managed by the second device, wherein the first device is configured to manage a first network where one or more devices capable of receiving a first service through the first device set to the gateway mode are present; confirm whether one or more available devices are present in both coverages of the first network and the second network upon confirming that the second device is set to a gateway mode based on the information regarding the mode of the second device; and determine whether to change the mode of the first device based on: presence or absence of the one or more devices that can be served by the second network from among devices in the coverage of the first network; and the mode of the second device, and change the mode of the first device from the gateway mode to a combined mode according to the result of the determination, and wherein the combined mode is a mode in which the first device operates as both of a gateway of the first network and a member of the second network, simultaneously.
 12. The device according to claim 11, wherein the mode of the first device is changed to the combined mode if the one or more devices are located outside the coverage of the second network or the one or more devices cannot directly receive a service of the second network through the second device although the one or more devices are located in the coverage of the second network.
 13. The device according to claim 11, wherein the mode of the first device is not changed to the combined mode if all devices that belong to the first network are located in the coverage of the second network and are available to receive the service of the second network.
 14. The device according to claim 11, wherein the mode of the first device is not changed to the combined mode if some devices belonging to the first network are not located in the coverage of the second network, but the remaining devices that need to use the service of the second network are located in the coverage of the second network. 